Mise au point18FDG et radiothérapie externe, le point de vue du radiothérapeute.: Application des techniques de fusion d’images à la radiothérapie des carcinomes bronchiques18FDG and external radiotherapy. The point of view of the radiotherapist.: Application of the techniques of fusion imaging to radiotherapy of non-small-cell lung carcinoma

The prognosis of patients with localized non-small-cell lung carcinoma and treated with radiation therapy remains poor. The three-dimensional conformational radiotherapy aims to increase the dose of radiation at the tumor volume to increase the local control, while sparing the healthy tissue neighborhood. The reduction of the safety margins and the irradiated volumes obliges to determine with most acute precision the exact tumor volume. However, the scanner alone is insufficient, particularly at the mediastinal level and at a distance. The positron emission tomography allows distinguishing a biological tumor volume. It helps to define the lung tumor volume, especially when the tumor is accompanied by atelectasis, and to recover the lymph node staging at the mediastinal level and at a distance. Even if the sensibility and the specificity are not 100 %, positron emission tomography now becomes essential before considering an escalation of thoracic radiation dose.